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An aqueous solution of CoCl2 on addition...

An aqueous solution of `CoCl_2` on addition of excess of concentrated `HCl` turns blue due to formation of

A

`[Co(H_(2)O)_(4)Cl_(2)]`

B

`[Co(H_(2)O)_(2)Cl_(4)]^(2-)`

C

`[CoCl_(4)]^(2-)`

D

`[Co(H_(2)O)_(2)Cl_(2)]`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the question, we need to understand the chemical behavior of cobalt(II) chloride (CoCl₂) when it is treated with concentrated hydrochloric acid (HCl). ### Step-by-Step Solution: 1. **Identify the Initial Compound**: The initial compound is cobalt(II) chloride, CoCl₂. In aqueous solution, CoCl₂ is typically present as Co²⁺ ions and Cl⁻ ions. 2. **Addition of Concentrated HCl**: When concentrated HCl is added to the CoCl₂ solution, it provides an excess of chloride ions (Cl⁻). 3. **Formation of Complex Ion**: The Co²⁺ ions can react with the excess Cl⁻ ions to form a complex ion. In this case, the complex that forms is CoCl₄²⁻. This occurs because CoCl₂ acts as a weak Lewis acid and can accept chloride ions to form a tetrahedral complex. 4. **Color Change**: The formation of the CoCl₄²⁻ complex results in a color change. The CoCl₂ in its hydrated form is typically pink (or deep magenta), but when it forms the CoCl₄²⁻ complex, it turns blue. 5. **Conclusion**: Therefore, the blue color observed upon the addition of concentrated HCl is due to the formation of the complex ion CoCl₄²⁻. ### Final Answer: The blue color is due to the formation of the complex ion CoCl₄²⁻.
To solve the question, we need to understand the chemical behavior of cobalt(II) chloride (CoCl₂) when it is treated with concentrated hydrochloric acid (HCl). ### Step-by-Step Solution: 1. **Identify the Initial Compound**: The initial compound is cobalt(II) chloride, CoCl₂. In aqueous solution, CoCl₂ is typically present as Co²⁺ ions and Cl⁻ ions. 2. **Addition of Concentrated HCl**: ...
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